The present invention relates to a suspension system for supporting the body of a motor vehicle on its rear wheels.
A conventional rear suspension system of a motor vehicle is disclosed in Japanese Unexamined Patent Publication No. 60-53408, for example. This suspension system comprises a swing arm extending in a longitudinal direction of the vehicle body and three independent suspension arms (lateral links) extending in a lateral direction of the vehicle body. One end of the swing arm is attached to the vehicle body in such a way that the swing arm can swing up and down while the other end of the swing arm is arranged such that it supports a wheel support member and transmits a force exerted in the longitudinal direction and a torque exerted in a turning direction of a wheel from the wheel support member to the swing arm. One end of each suspension arm is attached to the wheel support member while the other end is attached to the vehicle body, allowing each suspension arm to swing on its ends. Attaching points of the three suspension arms to the wheel support member are arranged such that they do not line up in a vertical plane oriented parallel to the longitudinal direction of the vehicle body. With this arrangement, the force (load) exerted in the longitudinal direction and the torque exerted in the wheel turning direction entered from the wheel are supported by the swing arm.
The swing arm extending in the longitudinal direction of the vehicle body carries the load exerted in the longitudinal direction and the torque entered from the wheel as well as a load exerted in the lateral direction of the vehicle body from the suspension arms attached to the wheel support member and a vertical load exerted from a suspension damper. Since the swing arm has to withstand all such loads, it has conventionally been a casting having a specific thickness, resulting in an increase in the physical size of the swing arm, an increase in unsprung weight, and a difficulty in improving ride comfort of the vehicle.
The invention has been made in the light of the foregoing problems of the prior art. Accordingly, it is an object of the invention to provide a suspension system which makes it possible to effectively decrease unsprung weight of a motor vehicle without producing such a problem as cracking of a swing arm.
According to the invention, a suspension system of a motor vehicle comprises a swing arm which is mounted to extend in a longitudinal direction of the vehicle body and has a fixing part for fixing a rear wheel support member, the swing arm including a main swing arm body mounted to extend in the longitudinal direction of the vehicle body with a forward end of the main swing arm body supported by the vehicle body, the main swing arm body having a support portion for supporting a suspension damper, a support member fixed to a rear portion of the main swing arm body, the support member having a supporting part for supporting a suspension arm, and a support reinforcing member for reinforcing at least the supporting part of the support member for supporting the suspension arm, wherein the main swing arm body, the support member and the support reinforcing member are produced by individually press-forming single steel plates and the swing arm is formed by joining the main swing arm body, the support member and the support reinforcing member.
This construction makes it possible to produce a lightweight, high-strength swing arm by joining the main swing arm body, the support member and the support reinforcing member which are made by individually press-forming single steel plates. Even if the wall thicknesses of the main swing arm body, the support member and the support reinforcing member are decreased, the main swing arm body supports a vertical load exerted from the suspension damper in a stable fashion while the support member and the support reinforcing member support a load exerted in a lateral direction of the vehicle body from the suspension arm in a stable fashion.
These and other objects, features and advantages of the invention will become more apparent upon reading the following detailed description in conjunction with the accompanying drawings.